. Transactions of the Royal Society of New Zealand. : \- ; >-. t£rot$a$xm$ Ifte ^ate?i Institute, Vol. xxi. S$$& m KM Thomas.—Geology of Tongariro and Taupo. 351 much more basic than any of the preceding rocks. It is heavyand black, with all the appearance of a basalt, and showsmicroscopic olivine. It contains, however, felspar and augitecrystals like the porphyritic crystals in the augite andesitespreviously described. They are not very abundant, and tothem are added olivine in numerous crystals, and felspar groundmass is in the main crystallitic, but shows farmore crys
. Transactions of the Royal Society of New Zealand. : \- ; >-. t£rot$a$xm$ Ifte ^ate?i Institute, Vol. xxi. S$$& m KM Thomas.—Geology of Tongariro and Taupo. 351 much more basic than any of the preceding rocks. It is heavyand black, with all the appearance of a basalt, and showsmicroscopic olivine. It contains, however, felspar and augitecrystals like the porphyritic crystals in the augite andesitespreviously described. They are not very abundant, and tothem are added olivine in numerous crystals, and felspar groundmass is in the main crystallitic, but shows farmore crystalline particles between crossed nicols, and glass isscarcely visible. The rock thus shows a relationship to theaugite andesites, but at the same time approximates to thebasalts. Another variety collected by Mr. Cussen containschiefly olivine among the larger crystals, though a few smalleraugites are present. The groundmass is partly crystallitic,but contains very numerous felspar laths. The analysis of the former variety by Mr. Pond shows
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1888
